Cross-connect cabinets and boxes perform a major role in the management of outside plant telephone cable installations. These cabinets serve as distribution and concentration points by which trunks carrying pairs known as "feeders" extending from the central office may be distributed among service subscriber telephone pairs. Typically, there are more service subscriber distribution pairs than there are central office feeder pairs. In the past, the usual convention has been to provide twice as many distribution pairs as there are central office feeder pairs. However, the modern trend is to maximize distribution plant utilization so that one and one half to one, and even one to one correlation between the number of feeder pairs and the number of distribution pairs is
presently proposed. More precisely the conventional cross-connect cabinet enables a feeder pair manually to be connected to any one of the subscriber pairs terminated therein.
Cross-connect cabinets usually are provided in standard sizes, such as 900 pair (300 feeder/600 distribution), 1200 pair (400 feeder/800 distribution), 1800 pair (600 feeder, 1200 distribution), 2400 pair (800 feeder/1600 distribution), 2700 pair (900 feeder/1800 distribution), 3600 pair (1200 feeder/2400 distribution), and 5400 pair (1800 feeder/3600 distribution).
Feeder cable is routed directly from a central office telephone switching facility to a cross-connect cabinet. Feeder cables are usually large (300 to 1800 pairs), and they are usually pressurized with dry gas. Since cross-connect cabinets have typically served as cable concentrators as well as distribution points, a higher percentage of feeder cable pairs ar likely to be in use than the percentage of distribution pairs in use. Conventionally, a feeder cable spans most of the distance from the central office to the service subscriber's location. In a residential neighborhood it is usual to find a cross-connect cabinet located within a few blocks of the subscriber.
Multi-pair distribution cables typically extend the distribution pairs from the cross-connect cabinet to terminal boxes at or very near the subscriber's premises. Terminal boxes are typically configured in multiples of 25 distribution pairs, with a corresponding number of subscriber drop pairs connected or connectable to the distribution pairs. In rural situations, terminal boxes come in sizes from 4 to 12 pairs, as well as 25. Terminal boxes are conventionally located so that they may be accessed by service personnel, but typically such boxes are not as accessible as cross-connect cabinets Terminal boxes may be located at ground level (pedestals), suspended aerially from telephone cable messenger wires strung between utility poles, and also inside of office buildings in telephone equipment rooms. Terminal boxes are not buried or otherwise placed below ground level in any environment subject to water intrusion, since they are not air tight. In some instances a breakout of four pairs is made as a direct splice in a distribution cable, and there is no external terminal box or block. These breakouts are usually installed when the distribution cable is buried, but remain idle until they are required.
Cross-connect cabinets end up servicing all types of telephone service subscriber groups. In general, however, these groupings fall into one or more categories of: rural, suburban, urban or commercial/industrial. The attributes of a rural cross-connect cabinet are that the service type is primarily residential and scattered over a wide service area. Numerous small terminal boxes are provided throughout the service area with multiple appearances of the distribution pairs Historically, there has been little subscriber service order activity
The attributes of a suburban cross-connect cabinet are that the service type is primarily residential and is distributed throughout a smaller area than the rural service area. Many small terminals (4-12 pair) or four pair breakouts are evenly spaced, with one terminal appearance provided for each distribution pair. A low to moderate amount of subscriber service order activity is encountered; however the level is higher than in the rural setting. Crossconnect cabinets in 1 suburban areas are typically readily accessible and are serviced more frequently than rural cabinets, due to the higher incidences of turn-up and turn-down service requests resulting from subscribers moving into and out of the area. Service calls to the cross-connect cabinet are limited by administrative procedures that call for leaving cross-connects in place after service to a particular residence has been terminated.
The attributes of an urban cross-connect cabinet are that the service type is typically residential and small business, with some data processing and special circuits. These urban cabinets are located in a small geographical area having a much denser population; and the attached terminal boxes are usually of the 25 pair type. These boxes are closely spaced together or are located inside of urban buildings; one terminal appearance is provided for each distribution pair. A moderate to high level of service order activity is encountered in connection with the urban cross-connect cabinet. Also, in the urban setting, cross-connect boxes may be much more difficult to reach and service.
The attributes of a commercial or industrial cross-connect cabinet are that the service type is medium to large business, with a high concentration of special circuits These commercial/industrial cross-connect cabinets are located in a small to moderate geographical area, and they serve large outside terminal boxes, or boxes inside of buildings; with one terminal appearance per distribution cable pair. A high level of change activity is encountered, with many turn up/turn down requests, as well as fluctuations in cable pair requirements for each facility serviced. Predicting such requirements is particularly troublesome for the operating telephone company, as businesses move into, and expand and contract operations within business parks. While access to cross-connect cabinets in business parks is readily available, due to the high service order change activity, substantial labor expense has been typically incurred in manually modifying the cross-connections between feeders and distribution pairs at the cross-connect cabinet.
One representative and typical facilities management system, known as "facilities assignment control system" ("FACS"), has heretofore been employed by operating telephone companies in order to control and record cross-connect cabinet pair assignments. FACS provides for entry procedures, cross-connect assignment control (including central office jumper assignment procedures), and data base updating facilities. FACS updates the data bases that keep track of all cable pairs and central office jumpers so that other administrative programs, such as the "central office maintenance program", and "line maintenance program" may function as intended.
One regional operating company has determined that approximately forty eight percent (48%) of all subscriber service requests can be handled by the FACS or a similar assignment program. That is to say, FACS can assign cable pairs, designate cross-connects to be made (or reused if the cross-connect already exists) and assign a CO jumper. If a new cross-connect is required, FACS provides for generation of a work order calling for a telephone technician to travel to the cross-connect cabinet to install manually a new cross-connect. In the other fifty two percent (52%) of the cases, FACS cannot make a cable pair assignment (and there are many different reasons for this inability), in which case manual assistance is required Typically, a Line Assigner makes the cable pair assignment and enters the assignment back into FACS. FACS performs the rest of tee operation (cross-connect assignment CO jumper destination, work order generation) automatically.
Although some remote controlled automation of some telephone outside plant switching functions has been proposed for certain limited and dedicated tasks, such as feeder trunk switching, see for example, U.S. Pat. No. 4,520,234 entitled "Remote Cable Switching System", which patent is commonly owned with the present patent, no satisfactory solution to the problem of remote automatic switching of distribution pairs to feeder pairs at the cross-connect cabinet has heretofore been realized The problem becomes particularly more challenging when it is remembered that a distribution pair should be accessible by a plural tty of feeder pairs, in order to assure availability of a feeder pair for each distribution pair, even though typically there are many fewer feeder pairs than distribution pairs concentrated at the cross-connect cabinet.
A remotely actuated telephone instrument connection block having instrument lockout and test features is described in U.S. Pat. No. 4,434,328 to Gary C. Fields. While the invention described therein permitted an operator at the central office test board to conduct certain tests and to disconnect telephone service at the subscriber's premises, the remote line disconnect block was limited to a single subscriber and did not have any automatic access features.
In the preparation of this patent application, several other patents were considered in addition to the above-referenced U.S. Pat. Nos. 4,520,234 and 4,434,328. These other patents include U.S. Pat. Nos. 3,562,435 (Joel Jr.); 4,639,557 (Butler et al.); 3,822,367 (Humphrey); 4,076,970 (Lubarsky, Jr., et al.) 4,029,913 (Gunderson); 3,920,927 (Russel et al.); 2,981,804 (Abbot et al.) and 2,925,473 (Lucas).
The Joel Jr. patent proposed a teletypewriter controlled X-Y crossbar switch placed between outside plant feeder pairs and the main distribution frame within the central office as a replacement for the manually patched central office cross connects
The Butler et al. patent describes a special test computer for testing e.g. special service or private line telephone circuits at a central office from a remote control point. The special computer includes both an analog bus and a digital bus. Voice synthesized error messages and frequency encoded communications means are stated aspects of the Butler et al. patent.
The Humphrey patent describes another line circuit testing arrangement for private lines. In this arrangement, a commercial telephone circuit from a main office becomes connected through a regional office to a private line extending to a local office of e.g. an insurance company. Impedances between the commercial lines and the private lines are equalized by the coupling units at the regional offices.
The Lubarsky Jr. et al. patent describes a telephone test system which uses a programmed microprocessor and a switching arrangement controlled by the microprocessor to select a particular telephone circuit and then connect it to a test port, thereby to enable tests to be conducted on that line via the test port.
The Gunderson patent describes a digital solid state telephone line test arrangement controlled from a remote control test center location. Extensive logic circuitry provides the test operator with considerable information regarding the condition of the circuit being tested.
The DeLuca patent provides a transition switch system for enabling telephone service subscribers to switch over from an older central office cross bar to a more modern electronic switch.
The Russel et al. patent describes an automatic switching arrangement within a private branch exchange which connects to any of a plurality of operator consoles. The arrangement enables the operator to connect a loop circuit to the trunk in a manner which enables the circuit so established to remain established while the operator console disconnects therefrom and is free to handle another service request. Thereafter, the operator console may reestablish connection to the established circuit, should that be desired.
The Abbott et al. patent describes a private branch exchange system which provides echelons of access to user circuits, some of which may have direct long distance calling access, and others of which have restricted access.
The Lucas patent describes a call concentrator which is preferably outside plant, located adjacent to the subscribers rather than within the central office environment. Time division multiplex is the preferred concentration technique.
With the ever increasing cost of service personnel labor, particularly travel time in the field, a hitherto unsolved need has arisen for automation of the manual cross-connection function between feeder and distribution pairs at the cross-connect cabinet.